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Outback driveshaft tunnel ice buildup

Just had our first snowstorm, about 5cm (2") of wet slush. After driving a few minutes I noted that I had a rumble from under the car when compression braking (manual transmission). Upon further inspection I noted that the driveshaft tunnel was completely packed with snow and ice. During compression braking the driveshaft must be moving upwards, contacting the ice buildup and rattling the floor of the vehicle.

My vehicle is a 2001 Outback wagon with 5 speed manual transmission.

This problem only occurs when the temperature is around freezing (0 to -5 celsius) and only with heavy wet snow and slush. AND it ALWAYS happens in these conditions.

Does anyone else have this problem?

Is anyone aware of a Subaru TSB related to this issue?

It seems that the Outback's exhaust heat shield which sits between the exhaust pipe and driveshaft is separated from the floor by about an inch or so. It is through this gap that the snow and ice is pushed up by the front wheels causing the problem.

It looks like spacers are used to separate the exhaust shield from the floor. Are these spacers unique to the Outback, or are they also used on the Legacy models? Every other vehicle (non-Subaru) that I looked at had the heat sheild separated from the floor by at most a 1/4 inch, while the Outback is 1 inch plus.

I am trying to design a shield that will attach to existing heat shield that will prevent snow and ice from getting in to the driveshaft tunnel. I may even need to shield the area around the transmission tailshaft/center differential housing.

My two previous Subaru's (1985 GL DR4WD GL wagon and 1993 Legacy L AWD wagon did not have this problem.

I've owned 2 OBW's since 97 and have encountered the same situation you describe only once, on the 97. The right combination of slush and a quick freeze gave me the same rumble from the driveshaft for 2 days until it warmed up and the ice melted from the heat shield. No big deal. It didn't damage anything, nor could it. It was annoying, but solved itself with a thaw. My 02 hasn't seen the same set of circumstances yet, and what are the possibilities of them happening again?

Has every chances of being an Outback only problem cause i drive in all kind of winter conditions here in Montreal and have never had such a problem with my Legacy.
Sometimes (rarely) the wheel wells get packed with wet snow but that's about all.

I'm from Canada and we see the conditions that cause this problem about every week or so from December until March.

I have already had a driveshaft replaced under warranty because a U joint failed, the dealer was unable to pinpoint the cause but having several pounds of rock hard ice rubbing on it can't be good.....

On a few occasions I have had the ice problem so bad that the U joint was totally encased in ice, even ice trough the yokes. Twice now, I have had to jack up the car and use a propane torch to cut out the block of ice.

I would like to eliminate this problem altogether by deflecting wheel spray away from this area.

The heat shield seems to be purposly made to catch the slush from the front wheels.......

I have had the wheel wells so packed with snow and ice that I could not turn the steering wheel more than a quarter turn in either direction. This problem plaques all cars, but my driveshaft tunnel is something unique to my third Subaru.

I spent 10 years in Montreal (3 with my Subaru GL and 3 with my Legacy). Never had this problem there, although the driveshaft on my GL did rust apart......

I think you are correct Josh. My wife's car is generally kept in a garage that never gets colder than 40 F in the winter (underground and often heated), and we have never experienced that problem in 4 winters (145k miles on it now) with the outback. It isn't practical from a cost standpoint for most people to heat their garage. Ours garage is mostly below grade and I heat it with wood, which is cheap around here.

Originally posted by Legacy777 park in a warm garage....that's about the only solution I can see.

Parking in a warm garage would melt the ice after a few hours, and is a trick that I used once.

But parking in a heated garage in areas where road salt is used will rust the car from the inside out. Taking a warm car into the cold causes condensation in the body panels and subjects the car to freeze-thaw-freeze cycles which are very hard on the panel joints, particularly rocker panels and door bottoms.

Annual rustproofing slows this rusting problem.

Since the Outback is my first Subaru that has this particular problem, it must be do to its design, which is why I am looking at the space between the heat shield and the floor panel so closely.

A company in New Zealand did make an undertray to protect the exhaust Y pipe from wheel spray. In 1989-1994 Legacy's, cracked Y pipes were common do to spray from the front right wheel. The updated part was a small spray deflector which prevented spray from hitting the exhaust collecter below the right head of the engine.

I am looking to do something similar to block wheel spray from getting between the heat shield and floor.

Originally posted by alias20035 But parking in a heated garage in areas where road salt is used will rust the car from the inside out. Taking a warm car into the cold causes condensation in the body panels and subjects the car to freeze-thaw-freeze cycles which are very hard on the panel joints, particularly rocker panels and door bottoms.

I have heard that before, and I don't know how true it is. In my case, if I want to park a car in the garage, it is going to melt even without the wood stove going. I only heat when I am working down there, but that is usually 3-4 days/nights a week.

I think a decent metal worker should be able to quickly fab a shield for you. Stainless steel (heavy) or maybe aluminum (lighter).

Originally posted by 99obw I think a decent metal worker should be able to quickly fab a shield for you. Stainless steel (heavy) or maybe aluminum (lighter).

I was thinking aluminum, and perhaps even rubber in areas away from the heat of the exhaust. There seem to be enough holes, bolts and other attachment points to make use of to attach the new splash shield.

Here is a photo of the underside of my car. Note the large space between the floor and the heat shield.

I think that slush sprayed against the heat shield is deflected onto the spinning driveshaft, which then deflects it against the floor panel where it freezes. Eventually enough ice builds up in the tunnel, and the driveshaft rubs it, particularly when decelerating.

Yesterday I drove less then two km in slush when I had to stop and crawl under the car to clear the ice. Yes, thats right less than two km!!! And I had to stop after another 10 km....

This used to happen about every week or two when I lived in Calgary, now that I am back in eastern Canada where I will encounter slush far more often, I am concerned that this constant icing problem will lead to mechanical problems with the driveshaft, u-joints and exhaust system.

Did I mention that the problem is so severe that the exhaust donut is pulled apart leading to the occasional backfire (or what sounds like a backfire)?